Turn east off the A1 in County Durham and you will stumble upon one of England's forgotten corners. This is a stark post-industrial landscape, yet infinitely varied and drably beautiful. Coal was once king here, but no more.

The Durham coalfields under the North Sea have closed, but they left a legacy: for 150 years, coal waste was simply dumped on the beaches, smothering the sand to a depth of 30ft in places. This brutalised shoreline was subsequently employed by sci-fi film directors in search of alien landscapes.

The sea has slowly washed away that mining waste and a huge community regeneration project, Turning the Tide, has transformed the area's superb coastline into a virtue – revealing the charms that made Lord Byron and Lewis Carroll linger here (Byron married the landowner's daughter in 1815 ... it didn't last) – and establishing a superb coastal route from Seaham to the edge of Hartlepool.

Seaham, once a Roman signal station buttressing the flanks of Hadrian's Wall, has also benefited from this regeneration, with new housing built on the site of the old Vane Tempest Colliery. Its lease on life is epitomised by the unexpected spectacle of a brilliant 1950s ice-cream parlour, Lickety Split, which even has a vintage Coca-Cola bottle dispenser. Seaham's church, St Mary's, is worth visiting, too, and is regarded as one of the 20 oldest surviving churches in the UK.

Grabbing an ice cream from Lickety Split, I headed south out of Seaham towards the giant windsocks at Nose's Point, where the legacy of all this environmental abuse is still apparent. Below was the burnished brown spectacle of Blast Beach, named for local pig iron blast furnaces, and once totally blackened by spoil from the mines.

The pit, which broke all European and national production records, closed in 1991 but oil and slag still discolour the rocks, although thanks to the efforts of local conservation groups and the inexorable rise and fall of the tide, things are clearly improving.

As you walk along the cliff there are a couple of easy paths down to the beach that make for a fascinating detour – but it's not a place to lay down a beach towel.

The cliffs here are formed from rare magnesian limestone – which is incredibly good for wildlife such as the northern brown argus butterfly – and the clean-up operation has helped the ecosystem to bounce back even more quickly than could ever have been hoped for. The area enjoys the status of one of Natural England's Sites of Special Scientific Interest, and the drama is enhanced by marooned sea stacks just offshore. Divers now regularly take to the waters, and have reported seeing octopus, velvet crabs, wrasse and lobsters, because the water's visibility, once zero, is now clear.

Back along the clifftop, the path skipped over the railway line and dived into the secluded ash and blackthorn woodlands of Hawthorn Dene, one of several glacial valleys cut into this coastline before passing underneath a striking railway viaduct. I emerged above Shippersea Bay with a backdrop of rolling hills, farmland and a mournful, solitary pit cage from the former Easington Colliery for company. Around Fox Holes Dene there were rows of classic terraced mining houses and superb coastal views north and south.

I climbed up steep Blackhills Gill then dropped down Limekiln Gill along a paved road to sea level. Heading south I crossed a footbridge at Denemouth, the head of Castle Eden Dene. It's a serene, haunting spot, the cliffs opening up and rivulets nudging here and there on their ambling journey to the North Sea, and the valley marshland framed by another spectacular railway viaduct. Castle Eden Dene is the largest of the denes along the coast and well worth visiting, either as a detour now, or, better, returning on a separate trip to spot the peregrine falcons that zip back and forth along the cliff edges.

One last hike took me up high on to the clifftop path, now overlooking Blackhall Rocks, the setting for the violent conclusion to the Michael Caine film Get Carter, which was filmed here 40 years ago. The film shows the beach blackened with coal spoilings, almost all of which have now been removed along with the mine's conveyor system and an unlamented concrete tower.

At Blue House Gill, I found myself walking over the filled-in shallow topsoil of Blackhall Colliery and encountered a colony of rare little terns, an encouraging sign that perhaps nature is winning the battle against the industrial legacy of pollution. I finished the walk, strangely, by threading my way – correctly – through a caravan site at Crimdon. Hartlepool loomed ahead, but beyond was the unmistakable ridge-like outline of the North York Moors.

From Seaham, head south past a roundabout to Nose's Point to pick up the footpath. The coastal route is clear enough from north to south, but involves several short detours inland to navigate around the denes or valleys. After the last of these, Blue House Gill, keep close to the coastline, passing a V-stile (grid ref: 474384). Follow the cliff contours and walk through successive V-stiles and then go left down and up steps to pass a substation (475382) and pass Crimdon caravan site on its coastal side to the car park (483373).

Compact Facts

How to get there

Seaham rail station is on the Durham coast line, with services from Newcastle and Sunderland. Services to Newcastle and Durham with East Coast Trains (08457 225225; eastcoast.co.uk). From Crimdon caravan site car park, take the No 25 bus to Hartlepool or to Durham/ Seaham via Peterlee (travelinenorth east.info). A taxi back to Seaham costs £10 to £15 with Red Stripe Taxis (0191-518 1111). A twin room at Seaham Hall (0191-516 1400; seaham-hall.co.uk) costs from £200 per night, including breakfast and entry to the hotel's Serenity Spa.